This section is intended to provide a background or context to the invention disclosed below. The description herein may include concepts that could be pursued, but are not necessarily ones that have been previously conceived, implemented, or described. Therefore, unless otherwise explicitly indicated herein, what is described in this section is not prior art to the description in this application and is not admitted to be prior art by inclusion in this section. Abbreviations that may be found in the specification and/or the drawing figures are defined below at the end of the specification but prior to the claims.
In a typical mobile communication system, a node or user equipment (UE) is connected to the network via a base station or eNodeB (E-UTRAN), either directly or through a relay station. Communicating device-to-device (D2D) is a subsequent development whereby the devices are typically user equipment. Communicating device-to-device can create an ad hoc network, whereby mobile nodes communicate directly with each other using wireless links.
A device-to-device communication system can be formed without an infrastructure, where such an infrastructure could be stationary and/or mobile. For instance, a device-to-device communication without a stationary base stations or a mobile relay station is possible.
The idea of clustering was introduced to form a more efficient ad hoc wireless network, wherein a group of nodes or UEs forms a specific group or cluster. The one node that coordinates the cluster activities inside the cluster is typically labeled as the clusterhead (CH).
In mobile ad hoc networks, CHs can be responsible for routing. Mobile nodes in a cluster first send their traffic to the CH and then the CH routes the traffic to other CHs until reaching the corresponding destinations.
While clustering has been discussed regarding ad hoc wireless communication networks, it is unclear as to how to implement a uniform UE initialization procedure for both in-coverage and out-of-coverage D2D communications.